Abstract

Changes in the activities of several antioxidant enzymes in transformed human dermal microvascular endothelial cells (HMEC-1) by infection with the obligate intracellular bacterium Orientia tsutsugamushi, the causative agent of scrub typhus, were investigated. The activities of glucose-6-phosphate dehydrogenase, catalase, and glutathione peroxidase were significantly decreased in HMEC-1 cells infected with O. tsutsugamushi. However, the level of superoxide dismutase increased slightly. Furthermore, increased levels of intracellular peroxide was observed in HMEC-1 during infection. These results support the hypothesis that cells infected by this intracellular bacterium experience oxidant-mediated injury that may eventually contribute to cell death.

• Keywords: Orientia tsutsugamushi; HMEC-1; antioxidant enzymes; intracellular peroxide; oxidative injury